GYEODACTYLID^. 51 



non of alternate generation or of digenesis, as Von Siebold supposes, 

 but a simple viviparous reproduction." 



Genera. — Gyrodactylus, ISTordmann ; Dadylogyrus, Diesing ; 

 Galceostoma, Van Beneden ; Tetraonchus, Diesing ; I)i;plectanumy 

 Diesing. 





